Social Wasps

All of the social wasps belong to the Super-family Vespoidea, and there are also brought into it a number of solitary wasps, as well as the so-called cuckoo flies of the old family Chrysididae, and some strange insects that were formerly placed in the parasitic family Proctotrypidae, but which are now made a family by themselves under the name Bethylidae. There are other parasitic groups in this super-family, and it also contains the curious creatures known as cow-killers, cow-ants, solitary ants, or velvet ants of the family Mutillidae, which have solitary habits, but closely resemble the true ants.

All these forms, differing however widely in habit, feed for the most part in their early stages upon other insects or upon the remains of other insects. The only exception is a small group found mainly in tropical regions, which may be termed the honey wasps, of which the old Polistes mellifica of Say, which comes from Mexico, is an example. all of these honey wasps are now brought together in one genus, which is called Nectarinia.

The true social wasps, nearly all of which in the United States belong to the Genera Vespa and Polistes, form communities much like those of the social bees. Their communities, however, are not so perfect and are not so persistent as are those of the true honey bee or of the ants, but resemble more nearly those of the bumblebee. There is a form known as the worker, just as with the social bees, and the workers here, as in the other cases, are undeveloped females. Here also, as with the social bees, these undeveloped females or workers may lay eggs which invariably produce males or drones.

Most of our social wasps make paper combs and nests. They are in fact the original paper-makers, and it's quite within the possibilities that the paper-making idea in the human species was gained from the observation of these insects. Their paper, however, is made from wood pulp - a late development in the human scale of ingenuity. They are particularly fond of scraping the frayed wood fibre from old weather-beaten fence boards and from the sides of unpainted buildings. These wood fibres are macerated with their saliva, and a pasty wood pulp is thus formed with which the nests are constructed.

In our consideration of the preceding group of wasps, we said something about individuality among these creatures and it: influence upon theories of instinct. In the social wasp also at least one observation seems to show that individuals in the face of an emergency previously unknown to the species readily adapt themselves to new conditions. This observation was made by Miss Mary E. Murtfeldt, of Kirkwood, Mo., who found that in a vineyard where the grape clusters were inclosed in paper bags to prevent destruction by insects the social wasps found that the damp and rotting paper bags were perfectly adapted to their nest building operations, and they thus used this paper already prepared rather than to take the trouble of manufacturing their own wood-pulp paper. This was a good thing for the wasps, but unfortunate for the vineyardist.

It is more difficult to study the economy of the social wasps than that of either the hive bee or ants. As most of the species are very irritable and possessed of venomous stings, it requires considerable tact and courage to investigate their habits closely. The size of the communities varies at the season when they are largest, and according to the species, from a few individuals to many hundreds. In one large nest I counted 1,135 cells, and since, as will be shown, the worker cells are used two or three times in the summer, the colonies become very strong. This count was made with the large bald-faced hornet (Vespa maculata) but in some of the smaller wasps or yellow-jackets, like Vespa germanica, the cells are even more numerous. In one nest of the latter species, Mr. Marlatt tells me that he carefully estimated that it contained about fourteen thousand cells.

These communities of the social wasps, unlike those of the hive bee and of ants, but like those of the bumblebees, have only a temporary existence. On the approach of winter the males and workers perish and the fertile females crawl into such protected situations as crevices in wails or under the bark of trees and there pass the winter in a dormant state. At the opening of spring each surviving female founds a new colony. At first she performs the duties of both queen and worker; a small nest is made, eggs are laid in it, and when the larvae hatch they are fed and cared for by the queen until they reach maturity. This first generation is composed entirely of workers. They relieve the queen of the duties which belong to them and from this time forth her only duty is to lay eggs. Sometimes she assists in the care of the young but not in the construction of the nests.

The essential part of a wasp's nest consists of a comb formed of hexagonal cells similar in form to the cells of a honey-comb. It differs, however, in several important respects from that of the hive bee: The material of which it is made is paper instead of wax ; the comb consists of a single layer of cells instead of two, and the cells are usually vertical instead of horizontal. In some species the nest consists of a single comb with one or more stems holding it in place. In others the comb is enclosed in a spherical envelope of paper with a small opening at the bottom. In the more complicated nests there is a series of combs placed one below the other, and the whole is enclosed in a case made of many thicknesses of paper. The nests are enlarged by adding cells to the edges of the combs, and room is made for these new cells by removing the inner layers of the envelope; the portion removed, however, not being wasted, but chewed up again by the wasps and added to the outside. The nests are suspended from branches of shrubs and trees or from fences and roofs. Some of the smaller species build their nests in the ground and under stumps. In each cell of the comb an egg is laid. Owing to the position of the comb, when the larva hatches it is suspended head downwards in each cell and holds its place while young by means of a glue and when old by its enlarged head end, which completely fills the open part of the cell.

They are constantly nursed by the females and workers, and are fed with a brownish fluid which is prepared by the workers or females and consists of the juices of fruits and the remains of other insects which have of been chewed up. When it gets full grown the larva spins a silken cocoon, the lower end of which serves as a cap to the cell, and then it transforms to a pupa. After the adult wasp is- sues the cell is cleaned out by the workers, and is used again by the queen, and, as the whole period from the laying of the egg to the emerging of the full-grown wasp is about a month in the northern states, a comb made early in the season serves for several successive generations.

As a rule the males and queens are not developed until toward autumn. At this time larger cells are made for the reception of the eggs which are to produce these forms. Thus if a large wasp nest be examined it will be seen that the top combs contain smaller cells and all of the same size, while the lower combs contain larger cells. This habit which the social wasps have of beginning at the top and building downward was what suggested to Gulliver's Laputan philosopher that they should be- gin by building the garrets of every house first of all and then gradually working down to the lower stories and the cellars.

The most notable of the social wasps in the United States is the bald-faced hornet (Vespa maculata) above referred to. It builds the enormous paper nests commonly seen attached to the branches of the trees. The great Vespa crabro or hornet of England and Europe, which is the species most cornmonly referred to in English books of reference, was accidentally imported into this country many years ago and established itself in the vicinity of New York City. I believe it was first discovered there by Mr. James Angus. It has since spread and multiplied very slowly, and is not known to occur very far from the place where it was originally discovered. It is rarely found in parts of Long Island and New Jersey. There is also an unconfirmed report of its establishment near Charleston, S.C. This wasp, which is more yellow in color, builds preferably in the trunks of old trees.

The smaller yellow-jackets (Vespa germanica and V. cuneata) build their nests above ground, in or beneath stumps or stones, and in excavations in the open ground. The underground nests are frequently very large, sometimes more than the size of a half- bushel basket. Access to these nests is gained by a single (rarely two) small opening which leads directly from the center of the nests. The loose paper covering is not as tough and thick as that with the big hornet.

The other common social wasps found in this country belong to the genus Polistes. They are the long-bodied, black wasps with folded wings and slender abdomens. They are frequently found in houses in the autumn looking for places to pass the winter. The nest of the Polistes wasps consists of a single comb without any envelope. They are found commonly in country barns, and are also attached to bushes and to the lower surfaces of stones which are slightly raised from the ground. They are generally horizontal in this country, but European species build their combs vertically. Polistes feeds upon caterpillars and also vegetable material as well, and its habits in other respects are very much like those of the other social wasps.